About an hour's drive east of San Francisco, steady winds blow about half the year through a stretch of terrain dotted with thousands of electricity-generating turbines.

Since the 1960s, Altamont Pass has been a proving ground for wind power. Now it's a test bed for solutions to one of the industry's biggest downsides: Turbines kill thousands of birds and bats annually.

Over the past several years, wind companies operating at Altamont Pass have made strides in reducing bird deaths across the wind resource area's 58 square miles (150 square kilometers). Part of the progress has come from shutting down in the winter months when the winds are low, and also from removing particularly hazardous turbines. (See related: "Notorious Altamont Wind Area Becomes Safer for Birds.")

Now a larger effort, overseen by the wind operators and the counties spanned by Altamont Pass, is under way to "repower" the area, or decommission old turbines and replace them with new ones that, ideally, will kill fewer birds. Alameda County is close to approving a one-year trial at Altamont of lower, "shrouded" turbines made by the Massachusetts-based company Ogin, according to county planning official Sandra Rivera. The new turbines have bonnet-like flaps that ring the perimeter of the turbine. The compact design is meant to boost efficiency, sit below a typical bird flight path, and deter a bird's flight into the rotors.

Trade-Offs With Newer Turbines

Thousands of older turbines at Altamont Pass have been fast-spinning and low to the ground, while also featuring cage-like lattice towers that were attractive places for birds to land and perch: a bad mix.

Most of these are being replaced by "monopole" towers, some as high as 500 feet (152 meters). The new towers are meant to be safer for wildlife, but a recent study suggests that may not be the case. Looking at hundreds of published reports on bird deaths at 59 wind farms across the United States, Oklahoma State University ecologist Scott Loss says the shift to the new, monopole designs is no simple fix.

The larger, more efficient structures appear to kill more birds per turbine than the windmills they're replacing—between three and eight birds per turbine per year, according to Loss. "Despite assertions that these turbines would reduce mortality rates, cumulatively they could still be responsible for a lot of mortality," said Loss, a co-author of the study. (See related story: "Sizing Up Wind Turbines: Bigger Means Greener, Study Says.")

One of the problems, Loss found, is that taller turbines kill more birds, particularly high-flying raptors and migrating waterbirds. So the benefits of the monopole design, and of having fewer, more efficient turbines, may be offset by the fact that new turbines are taller and tend to have larger rotor spans. At Altamont Pass, older lattice towers tend to range in height from 60 to 80 feet (18 to 24 meters). Newer models being installed are, in many cases, four to five times taller.

Loss estimates that between a quarter to half a million birds are killed by the new, larger turbines each year, a number that is sure to increase as wind power projects proliferate. Concern over bird deaths has derailed multiple high-profile wind energy projects recently, including a wind farm in the United Kingdom that conservationists claimed might threaten an endangered water bird.

Bird's-Eye View

In a bid to increase visibility to birds, turbines have been painted in high-contrast colors, fitted with noisemaking devices or lit with UV lamps to alert birds to spinning blades, but the efficacy of these experimental measures is so far unclear. In Spain, wind energy companies have worked with scientists to shut down wind farms when large numbers of migrating birds approach, a move that seems to work.

Researchers are beginning to look at the problem from a bird's-eye view, so to speak. Graham Martin, an ornithologist at the University of Birmingham in the UK, has conducted experiments with large migratory birds to understand how they see. It turns out birds don't pay much attention to what's ahead of them. They're focused instead on the ground or the area to their sides-either because they're hunting or looking for places to land. "People make easy assumptions that it's enough to stick something on a wire or paint blades," says Martin. "But the way we see these things is quite different than the way birds see them."

That may mean designing wind farms differently, perhaps by creating large areas on the ground that tempt the birds to descend to lower altitudes, out of the way of spinning turbine blades. "If you are trying to design something to alert birds to what's ahead, it's probably got to be a lot bigger and grander than you're thinking," Martin says. "You can't just make turbines more conspicuous."

That's a problem for the wind industry, which usually rents or leases space for windmills from farmers or other landowners but doesn't control the surrounding fields. "Less than two percent of the land area is permanently occupied by the infrastructure of a wind farm," said John Anderson, director of siting policy for the American Wind Energy Association. "Farmers are going to want additional compensation for measures like that." (See related story: "Planting Wind Energy on Farms May Help Crops, Say Researchers.")

There are other alternatives, of course: The U.S. Department of the Interior this month released a strategy to mitigate the impact of development projects, including wind farms, on birds and other wildlife. The plan focuses on putting windmills in places where they'll make the least impact, rather than trying to protect birds after the fact.

But the department also issued a rule last December that would grant 30-year permits to wind facilities allowing for limited numbers of eagles to be killed, granting them only to applicants "who commit to adaptive management measures to ensure the preservation of eagles."

The federal rule regarding these extended "take permits," as they are known, met with sharp criticism from conservationists. David Yarnold, head of the National Audubon Society, wrote in January that though "Audubon strongly supports properly-sited wind power," the Interior rule has "highly questionable conservation value," and called the department's assurances that there would be five-year inspections to police the rule "bureaucratic vapor." (See more about take permits and Audubon's take on eagles and wind farms here: "Wind Farm Faces Fine Over Golden Eagle's Death.")

Ultimately, though, no technology is without costs—and the advantages of renewable wind power over, say, coal-fired power plants may outweigh their impact on bird species. "Saying wind power can only be green if there are no impacts is like saying medicine can only be effective if it has no side effects," Anderson says. "At some point, we need to put the benefits and risks into context."

Oklahoma State's Loss, for example, notes that American homes and office buildings are responsible for hundreds of millions of dead birds per year, many times more than windmills. And researchers recently estimated that house cats kill well over a billion birds in the United States annually. "Comparing our numbers to total bird numbers, they might seem small, but that doesn't mean we shouldn't focus on local impacts on specific species, especially long-lived species like raptors or waterbirds," Loss says.

As wind energy proliferates in response to concerns over climate change, researchers will continue to work to mitigate its impacts. "We have to work around the birds—you can't just wag your finger and tell the birds to learn," said Martin. "There are no quick, easy fixes." (Take the related quiz: What You Don't Know About Wind Power.)

On top of wind turbines and cats, pesticides kill birds and bats. Pollution, hunters, poachers (mass killings included in hunters and poachers), solar farm and wrong solar panels (or wrong generators) kill birds, habitat loss due ongoing and massive deforestation and loss of wetlands/grasslands on top of that..It all ads up and is indeed not a small amount of winged animals that gets killed per year (worldwide).So we must do whatever we can to protect what we have left on birds.Birds are as important than bees and trees and without them we cannot survive.They act as pollinators, insect/rodent control and seed distributors for other plants to grow.The more birds and bats we kill the more and stronger herbicides, pesticides and insecticides we will need until we extinct ourselves. ..

In my opinion the low mortality estimates given in the study were the
primary purpose this study was written. These new estimates have even lowered
the old 2009 FWS number of 440,000 bird fatalities per year, which was based
upon 25,000 MW.

The estimates from this study and the old FWS mortality estimates are not
even close to being accurate because of the unreliable data used to get these
estimates.

A
single 40 kW turbine has a rotor sweep of 154 Sq meters or 51 times
smaller
than a modern 2.5 MW turbine. A single 100 kW turbine has a rotor
sweep of 254 square meters or 25 times smaller than a 2.5 MW turbine. These
small turbines were the primary turbines mounted on lattice towers. Industry
carcass searches around these turbines were 50 meter from towers and still are
being used at Altamont
Pass.

The
total wind industry mortality search area around 51 small 40 kW
turbines
amounts to about 400350 square meters. Today a carcass search area on a
modern
2.5 MW turbine is about 7850 square meters and can sometimes even be far
less.
I have looked over one industry study that only looked for carcasses in
area of
about 1300 square meters around the 2.3 MW turbines in the study.

Today
in the US there are
about 61,000 MW of installed capacity.Accounting for the wind industry's flawed
study methodology and their grossly undersized search areas, the true mortality
to birds exceeds 6 million birds per year in the US.

This study relied on the wind industry's own bogus data and did not account
for the undersized search areas being used by the wind industry. They did make some
adjustments for varying search radius, but these adjustments accounted for
small differences in the search area size used from site to site. The study's
discussion of the mortality search area adjustments that were made is very
deceptive because when they did not account for industry search areas that are
as much as 90 times too small.

This study failed to point out several important facts about the use of
monopole mounted wind turbines. As the industry began installing these types of
turbine towers and moved away from the lattice towers, tower height and turbine
blade length increased dramatically. Wind turbine towers have grown from about
20 meters to 100 meters and blades have increased from 7 meters on 40 kW
turbines to over 50 meters in length. Instead of increasing carcass search
areas in their mortality studies to accommodate these progressively larger
turbines, the wind industry has deliberately stayed with their search areas of
about 50 meters from towers even though their new turbines are as much as 51
times larger.

All the estimated bird mortality at monopole wind turbines in the contiguous
US is derived from mortality studies rigged to miss most of the turbine related
mortality. These are studies with small designated search areas that pretend
that carcasses landing beyond these designated search areas do not exist.

Ok, Now that I have done some research of my own I can see why those old wind farms were so damaging to the birds. With their very small size and the fact that their blades were spinning very rapidly it makes perfect sense why they were killing so many birds.

HOWEVER, to compare the newer wind generators to those is like comparing the old windmills that farmers used to use. These newer ones are 2 to 4 times higher and their blades spin VERY SLOWLY!!! So the birds can actually avoid the blades. But because the blades are over a hundred feet long they pick up the force of. He wind over their entire length and have an extremely high amount of torque. So they can spin larger generators inside and are much more efficient.

So, I see no problem with these newer wind generators. I even took a short road trip to the "Thumb Area" of Michigan where they have been installing many of the new wind generators, And Guess What.... They were very quiet and I didn't see a single dead bird at over 35 of them. So I see nothing but blue skies and no ugly smoke stacks in Michigan.

Maybe those people that are on the fence should take a small trip and actually see what they are like CLOSE UP!!!

Even when Wind Turbines kill far fewer birds per an amount of energy than oil and coal, the Wind Energy industry is still willing to push to improve it's standards, to become closer to the current conversationalist leader, Photovoltaic Solar.

Can all those that feel industrialize vast swathes of nature please explain why this is a good idea...when spending money on insulation, high efficiency equipment and lights...is more cost effective and drops demand greatly. Also group geo thermal projects do much more to save CO2. Wind Turbines work at 30% of capacity and require 100% backup and lots of equipment and then are left to rot when broken. They are a bad solution to the problem. Can you honestly say that industrialization of vast amounts of nature is a good solution? We can do better!

Sadly many have sold their environmental souls to pursue wind energy and make money! They will lie upfront, during and after swearing there will be no harm, there is no harm and nothing happened. They do everything in their power to look for kills in the wrong places or just not to look. In NJ & DE wind turbines have been documented to kill 80 plus bird per year per turbine. In PA documented 25 bats plus for every turbine on top of white nose syndrome! They don't openly admit it, and they don't stop the kills. I am working against Mass Audubon Society and their Wellfleet Bay Wildlife Sanctuary who are attempting to erect turbines in their WILDLIFE SANCTUARY! The feel good nature of these projects are so powerful they lie to themselves and others about the harm that will occur...and make "promises" they have NO IDEA ABOUT! The US FWS promised no Bald Eagles would be killed when they erected a small wind turbine in the Eastern Neck Wildlife Refuge in Maryland. Problem was the Eagles didn't know and one got killed. Then the expensive project broke in a WIND STORM! There are so many LIES in the renewable community...it is almost impossible to get the truth. Bird and bats are dying in the millions across the world FACT. The false argument that Global Warming is killing animals that have existed with all kinds of weather across the millennia is so feeble...it is, in your face LAUGHABLE. STOP LYING ABOUT THE HARM. Golden Eagles are being decimated in California. The one study of radio tracked Eagles in California showed the turbines are the NUMBER 1 killers. The money for wind and solar would be better used to lower demand through efficiency and conservation...problem is many insiders would lose their millions in payoffs. This will go down as the most shameful environmental sell out in history. The harm will be realized for decades...with many birds and bats disappearing!

This study relied on the wind industry's own bogus data and did not account
for the undersized search areas being used by the wind industry. They did make
some adjustments for varying search radius, but these adjustments accounted for
small differences in the search area size used from site to site. The study's
discussion of the mortality search area adjustments that were made is very
deceptive because when they did not account for industry search areas that are
as much as 90 times too small.

This study failed to point out several important facts about the use of
monopole mounted wind turbines. As the industry began installing these types of
turbine towers and moved away from the lattice towers, tower height and turbine
blade length increased dramatically. Wind turbine towers have grown from about
20 meters to 100 meters and blades have increased from 7 meters on 40 kW
turbines to over 50 meters in length. Instead of increasing carcass search
areas in their mortality studies to accommodate these progressively larger
turbines, the wind industry has deliberately stayed with their search areas of
about 50 meters from towers even though their new turbines are as much as 51
times larger.

All the estimated bird mortality at monopole wind turbines in the contiguous US
is derived from mortality studies rigged to miss most of the turbine related
mortality. These are studies with small designated search areas that pretend
that carcasses landing beyond these designated search areas do not exist.

In my opinion the low mortality estimates given in the study were the
primary purpose this study was written. These new estimates have even lowered
the old 2009 FWS number of 440,000 bird fatalities per year, which was based
upon 25,000 MW.

The estimates from this study and the old FWS mortality estimates are not
even close to being accurate because of the totally unreliable data used to get
these estimates.

A single 40 kW turbine has a rotor sweep of 154 Sq meters or 51 times smaller
than a modern 2.5 MW turbine. A single 100 kW turbine has a rotor
sweep of 254 square meters or 25 times smaller than a 2.5 MW turbine. These
small turbines were the primary turbines mounted on lattice towers. Industry
carcass searches around these turbines were 50 meter from towers and still are
being used at Altamont
Pass.

The total wind industry mortality search area around 51 small 40 kW turbines
amounts to about 400350 square meters. Today a carcass search area on a modern
2.5 MW turbine is about 7850 square meters and can sometimes even be far less.
I have looked over one industry study that only looked for carcasses in area of
about 1300 square meters around the 2.3 MW turbines in the study.

Today in the US there are
about 61,000 MW of installed capacity.Accounting for the wind industry's flawed
study methodology and their grossly undersized search areas, the true mortality
to birds exceeds 6 million birds per year in the US.

Of course mortality increases with increasing height of monopole turbines.
The rotor sweep can be as much as 51 times greater when compared to turbines
mounted on lattice towers. These huge turbines mounted on monopole towers have
always killed far more birds per turbine. Any modern turbine with 51 times more
rotor sweep mounted on an 80 meter tower is going kill far more birds than any
small turbine mounted on a shorter 24.6 meter tower.

Some of these huge turbines are killing over 1000 birds and bats per
year and
even with grossly undersized search areas, searchers are finding far
more
bodies in the industry's tiny search areas around each tower. They did
not need
a study to figure this out.

"Mortality rates appear to be lower in the Great
Plains relative to other
regions"

The Great Plains region has experienced the
greatest amount of wind energy expansion in the last 7 years. This expansion
has included the installment the industry's most modern and largest turbines.
These are turbines that should also have the largest search areas because
carcasses can be found in areas of at least 200 meters in all directions from
towers. The industry has instead used their grossly undersized carcass search
areas in this region.

The
Great Plains region is also plagued with
another problem that impacts reported mortality. This region has the most
agriculture taking place around installed turbines. This agriculture plows and tills
carcasses into the ground. As a result many carcasses go undetected by industry
searches.

Sadly
this was a "peer reviewed study". As a result the low mortality
estimates given in this study will be quoted in the media, quoted in
future
studies, and used to mislead communities from knowing how devastating
these
turbines are to birds and bats living in their communities.

For more information on how
the industry rigs their mortality studies everyone should read this article
and the comments on the Ecoreport

The hypocrisy of liberal environmentalists never ceases to amaze me. They were willing to basically ruin the northwest lumber industry, causing loss of hundred if not thousands of jobs and availability of building supplies for the sake of a spotted owl habitat, yet the demonstrated damage to dozens of species of migratory birds, noise and sight pollution, and the yet to be realized weather consequents of these wind turbine farms.

Wind turbines only kill about one in 86,000 birds annually in the USA. This isn't an issue outside of places like the Altamont Pass where the most avian-unfriendly wind generators were placed en masse directly in raptor migration and soaring routes. This is a vastly overblown issue, as every study ever done of avian impacts from different forms of generation has found that wind energy has the lowest wildlife and avian impacts. According to one credible study, fossil fuel generation has 17 times the avian mortality impacts of wind energy. Other studies show that global warming puts up to 50% of avian species at risk due to loss of habitat for nesting and safe migration.

The wind industry is taking this very seriously not because they have an empirical problem compared to other forms of generation, but because anti-wind forces continue to whip up this non-story into a controversy and organizations such as National Geographic continue to not do due diligence regarding comparative mortality.

Scott Loss is also lacking perspective. Due to the massive increases in scale of wind generators, 100 devices such as exist in Altamont Pass will be replaced with roughly 16 modern wind turbines generating perhaps 30% more electricity annually. The mortality per device isn't a useful metric, the mortality per MWH or per square mile is, and on both of those counts modern wind energy is much better than the older generators in the Pass.

As for Ogin, I've read their avian mortality submission and the comments. They only want to compare their mortality rate to that of the very bad 30-40 year old technology, not the modern technology which has much lower impacts. Understandably, many people are clear that this is inadequate, and they are facing stiff headwinds in gaining approval for a very small test facility alone according to what I've seen. Their technology is also very small scale, in the 100 KW range compared to modern turbines 1.5-3MW. They are much closer to the ground where the wind resource is lower. They will have similar spacing to the older turbines as a result, with slightly better avian mortality due to monopole construction and -- maybe -- their shroud which creates its own problem of excessive cost per KWh. I expect that Ogin will continue to suck R&D grants out of governmental agencies without actually delivering any significant amounts of electricity to the grid at anything like the current excellent price of modern wind turbines. It's noteworthy that the highest outlying number for avian mortality of 573,000 annually is by Shawn Smallwood, the biologist engaged by Ogin for their site studies. Median numbers by more credible teams put the number around 234,000 annually.

Wind turbine blades kill thousands of migratory birds and harm wildlife
while they produce electricity. Cape Wind in Nantucket Sound will kill thousands of Roseate Terns. Massachusetts has made Cape Wind pay $750,000.00 in advance. Cape Wind is going to build 130 antiquated gear driven 3.6 megawatt turbines. These type turbines are no longer used on land as the gear boxes need to be changed every three to five years. The maintenance on Cape Wind will destroy all migratory sea life as they change gear boxes for years. A total failure of " Due Diligence"

Wind turbines are noisy, which bothers the
people who live near them and they can't sleep. Wind power projects often
include government giveaways of public lands to private wind farm developers.

Some people believe that wind turbines are ugly and spoil the scenery. I
think they look like giant upside down tooth brushes sticking out of a
toilet.

Wind turbines lower local property values by 22 to 27 percent, harming
local homeowners. Wind energy is still more expensive than electricity produced
by other sources such as natural gas by 3 to 4 times as much.

Wonder whether some kind of high-pitched noise, from that of a predator like a hawk, could be emitted at the top of the turbine every 30 seconds or so, getting the birds' attention? It needn't be so loud that any human ear on the ground could hear it. Something like that may virtually eliminate these bird deaths.

I frequently wonder why they don't install small flaps on the end of the turbine blade similar to the flaps on the end of a jumbo jet? It seems to me like it would increase the visibility AND efficiency of the entire turbine! Has anyone also tried using horizontal turbines instead of vertical? These may make a big difference.

Visually, modern wind turbine rotors seem to spin slowly. But realize the tip speed of these 50m long rotors can travel 300km/h (186.41mph)!

Birds in flight on these heights do not look ahead (since naturally there should not be any obstructions), and they definitely are not used to objects moving at such high speeds!

Short visits to wind farms do not give any useful information. The way sound travels depends on many different conditions and cadaver count of dead birds/bats is not that simple as just to pop by and have a check once in a while.

@Mike Barnard Mike you are a LIAR! In PA alone more than 10000 bats die! In NJ and DE each turbine is killing 80 plus birds/bats per turbine! Even the most ardent supporters would admit your numbers are a complete fabrication! Is this from the American Wind Energy Association Lobbyist The lobbying group complete fabrication about 1 bird per turbine? As you know most searches are done in a small square under the turbine...problem is most birds don't fall directly under the tower. I am sure you are very well paid to spread your falsehood. Your comment is so poorly written it is hard to understand if you think it is 86000 or 500000 or something inbetween. Since with each study the number increases with a factor more...you can be pretty sure the numbers are even higher. In Massachusetts where they are building lots of wind turbine(many mechanically breaking or being destroyed by lightning)....they don't even count the kills. Please explain why you think building lots of turbines where birds and bats are many and not studying or making public the number of kills is smart? Would you support actual study? Or do you just wish to do what the lobbyists says to do? Should we ignore the eagle and migratory bird laws...international treaties BTW? You do realize wind turbines work at less than 30% of their stated capacity and require 100% backup that needs to be paid for? And that very cost effective efficiency and conservation and geo thermal require no backup and work 100% of the time? Of course lobbyists can't make lots of money off cost effective ideas!

@Frank Haggerty I work in the wind industry. A lot of turbines (but not all) have gearboxes. There's an issue with gearboxes from some manufacturers failing, but they aren't built to fail. When failures happen, it usually generates a warranty claim against the manufacturer, so obviously manufacturers are working to reduce gearbox failure rates. Even if some gearboxes fail, I don't see how that would destroy all migratory sea life. If anything it would shut some turbines down for some time while they wait for replacement parts. Another thing is that turbines are pretty quiet. Ok - if you build one in somebody's back yard they might hear it, but from 100 yards or so a turbine is quieter than ambient noise such as wind rustling leaves in trees. These turbines are being built way off shore, so noise is not going to be an issue. Beauty is in the eye of the beholder, but at least I think they will look better than a big coal fired power plant on built on the cape. While there are indeed issues relating to bird and bad deaths (which the industry cares dearly about improving), these turbines will be less harmful to wildlife than a coal fired power plant. Wind energy doesn't have any fuel cost, so its cost is fixed and its competitiveness against coal and natural gas varies with the price of coal and natural gas. Wind can be very competitive and have a less volatile price over the long term compared with burning fuels which have unpredictable costs.

@LARRY MARTIN because they already only work at 30% of capacity and need to be cleaned to work at that...that screens would make them even more useless. Conservation and efficiency projects are more cost effective...require no destruction of land, wires or backup, work 100% of the time and save money!

@LARRY MARTINThis basically what the new wind turbine design has done. This turbine is being delayed with studies and politics so the truth about this bird safe turbine will allow the industry to sell more of their deadly propeller style turbines.